The invention is related to the field of gyroscopes and in particular to a gyroscope measuring a rotational rate as a function of the change in the propagation velocity of a surface acoustic wave.
2. Prior Art
Optical gyros which measure rotational rates as a function of the change in the length of an optical path are well known in the art. Examples of such optical gyroscopes are the ring gyro as disclosed by W. Macek and D. Davis in the publication "Applied Physics Letters," Volume 2, 1963, page 67, the fiber optic gyro as disclosed by V. Vali and R. Shorthill in the publication "Applied Optics," Volume 16, 1977, page 290 and the passive ring gyro as disclosed by S. Ezekiel and S. R. Balsamo in the publication "Applied Physics Letters," Volume 30, 1977, page 478. The operation of these optical gyroscopes utilize the fact that light travels at a constant velocity in an inertial frame of reference and the rotation of the gyro causes a change in the length of the light path between the source and the detector. Surface acoustic waves exhibit many of the properties of light waves; however, the velocity of the acoustic waves is not a constant in the inertial frame of reference. Therefore, one has to look elsewhere for a viable mechanism of the acoustic waves which can be used to measure the rotational rate of an inertial frame of reference. The disclosed invention is a surface acoustic wave (SAW) gyroscope which detects the effect of rotation on the propogation velocity of the surface acoustic wave.